Photonic crystal laser cavity with one-dimensional (1D) photonic bandgap is investigated by plane wave expansion method and finite-difference time-domain method. The photonic crystal laser cavity with quality factor Q of 2.2×106 and mode volume V of 0.278(λ/n)3 is achieved. The relationships between tapered section, mirror section, defect section, and Q are analyzed. The introduction of tapered section, choosing proper periodic number and suitable defect length can improve the performance of the cavity. These conclusions provide an effective theoretical analysis and guidance on optimization of photonic crystal cavity with 1D photonic bandgap.